The usual way of making a long distance telephone call by credit card is to first enter the long distance carrier's seven-digit access code, either alone or as an "800" number call. In either case, this obtains an audible dial tone which cues the caller to dial 0+Area Code+phone number called. With that properly done, an authorization code, usually of fourteen digits, must be entered. This authorization code is typically the caller's credit card number. Upon completion, the caller has entered a total of no less than thirty-two digits.
To overcome the obvious drawbacks of having to re-enter all of these digits to reoriginate a call (i.e., to place another call), a feature has been available from at least one of the long distance carriers whereby, prior to calling party disconnect (i.e., the calling party hanging up), a single key input from the caller's push-button phone is used to avoid a total reset which would require re-entry of all digits. The
single key used for this purpose is the # key, commonly referred to as the "pound sign" key.
This key generates a particular set of tones which is recognized as a reorigination request, causing a dial tone to be returned to the caller without the need for re-entry of the credit card number or of the long distance company's access code. The caller simply redials the area code and called party number after having used the # key. Multiple calls can be successively made without the need to regain access and re-enter the calling card number for each successive call.
While reorigination in this manner has been a significant improvement, certain problems have arisen in the rapidly changing telecommunications environment to defeat the total effectiveness of the present techniques.
At present, to achieve reorigination, the # key must remain depressed for a period of at least 800 milliseconds. This tone period is relatively long and was chosen to avoid spurious reorigination that can occur during the talking phase of a call (i.e., between answer and disconnect). The long duration serves effectively as a filter to prevent voice and background incidental tones from causing "talk off" of the system into reorigination.
While the long tone duration effectively avoids spurious reorigination of this kind, in certain stages of the call it is desirable to be responsive to short duration inputs since not all callers can be counted on to hold the key depressed for the full period. More importantly, however, certain telephone equipment, such as the newer PBXs and car phones, produce tone duration times of a fixed length irrespective of how long a key is actually depressed. These uniform pulses are typically quite short, an on the order of 70 milliseconds or so. The effect is that reorigination is rendered useless by this latest equipment since the short duration tones simply go undetected.
Thus, it is among the objects of the present invention to provide an adaptive reorigination method and apparatus which responds to shorter, uniform tone durations during certain stage of the call while preserving the longer filtering effect to avoid "talk off" reorigination during the talking stage (i.e., the communication stage) of the call.
It is also among the objects of the invention that it be adaptable to either automatically return dial tone to the credit card caller once the called party hangs up, so that reorigination can occur directly without the need to use the reorigination key at all in those circumstances, or to require use of a positive reorigination command.